Contributions of the atmosphere-land and ocean-sea ice model components to the tropical Atlantic SST bias in CESM1

Zhenya Song, Sang Ki Lee, Chunzai Wang, Benjamin Kirtman, Fangli Qiao

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

In order to identify and quantify intrinsic errors in the atmosphere-land and ocean-sea ice model components of the Community Earth System Model version 1 (CESM1) and their contributions to the tropical Atlantic sea surface temperature (SST) bias in CESM1, we propose a new method of diagnosis and apply it to a set of CESM1 simulations. Our analyses of the model simulations indicate that both the atmosphere-land and ocean-sea ice model components of CESM1 contain large errors in the tropical Atlantic. When the two model components are fully coupled, the intrinsic errors in the two components emerge quickly within a year with strong seasonality in their growth rates. In particular, the ocean-sea ice model contributes significantly in forcing the eastern equatorial Atlantic warm SST bias in early boreal summer. Further analysis shows that the upper thermocline water underneath the eastern equatorial Atlantic surface mixed layer is too warm in a stand-alone ocean-sea ice simulation of CESM1 forced with observed surface flux fields, suggesting that the mixed layer cooling associated with the entrainment of upper thermocline water is too weak in early boreal summer. Therefore, although we acknowledge the potential importance of the westerly wind bias in the western equatorial Atlantic and the low-level stratus cloud bias in the southeastern tropical Atlantic, both of which originate from the atmosphere-land model, we emphasize here that solving those problems in the atmosphere-land model alone does not resolve the equatorial Atlantic warm bias in CESM1.

Original languageEnglish (US)
Pages (from-to)280-290
Number of pages11
JournalOcean Modelling
Volume96
DOIs
StatePublished - Dec 1 2015

Fingerprint

Sea ice
sea ice
sea surface temperature
Earth (planet)
atmosphere
ocean
Temperature
thermocline
land
mixed layer
Temperature distribution
simulation
stratus
summer
surface flux
westerly
entrainment
seasonality
Water
surface layer

Keywords

  • CESM, Atmosphere-land model experiment
  • Implicit SST bias
  • Ocean-sea ice model experiment
  • Tropical Atlantic SST bias

ASJC Scopus subject areas

  • Atmospheric Science
  • Oceanography
  • Geotechnical Engineering and Engineering Geology
  • Computer Science (miscellaneous)

Cite this

Contributions of the atmosphere-land and ocean-sea ice model components to the tropical Atlantic SST bias in CESM1. / Song, Zhenya; Lee, Sang Ki; Wang, Chunzai; Kirtman, Benjamin; Qiao, Fangli.

In: Ocean Modelling, Vol. 96, 01.12.2015, p. 280-290.

Research output: Contribution to journalArticle

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AU - Qiao, Fangli

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